SIXTY-TWO SPECIES OF FISHES FROM LAKE ERIE 
371 
DESCRIPTION 
6 .6 -millimeter stage . — Total length, 6.6; length to vent, 4.1; length of head, 1.1; 
snout, 0.2; diameter of eye, 0.3; greatest depth before vent, 0.83; depth behind vent, 
0.87 millimeters. Myomeres, 22 to vent plus 16+ behind. Embryonic marginal 
fin fold originating dorsally over stomach region, rising to its highest point behind 
Figure 99. — Percina caprodes zebra, 6.6 millimeters 
vent, continuing around lophocercal tail, and similar in contour ventrally. Body 
elongate, rather compressed; mouth reaching past front of pupil, armed with sharp 
pointed teeth in both jaws; mouth subinferior' with very slight projection of snout; 
rudimentary air bladder; large pectorals. 
Pigmentation. — One large chromatophore occurs below base of each pectoral, 
three along ventral margin with the last at vent, one above this on dorsal surface of 
intestine, and a broken inconspicuous single series on ventral ridge to caudal. 
Figure 100. — Percina caprodes zebra, 12.15 millimeters 
12.15-millimeter stage . — Total length, 12.15; standard length, 11.2; length to 
vent, 6.6; length of head, 2.06; diameter of eye, 0.6; greatest depth before vent, 1.4; 
depth behind vent, 0.98 millimeter. Myomeres, 20 to vent plus 20+ behind. Ele- 
ments of 14 dorsal rays in marginal fin fold, and about 9 elements and 8 incomplete 
rays of anal directly below; tail becoming heterocercal and caudal rays forming. 
Pigmentation. — The marking is as in the preceding stage with 1 subsurface 
chromatophore below pectoral base, 1 or more along ventral margin of intestine, 
and about 4 or more large subsurface spots on ventral ridge of tail, the first of which 
is at vent. 
Ill- .2-millimeter stage . — Total length, 14.2; standard length, 12.6; length to vent, 
8.25; length of head, 3.0; snout, 0.67 ; diameter of eye, 1.0; greatest depth before vent, 
2.03; depth behind vent, 1.4 millimeters. Myomeres, 20 to vent plus 20+ behind. 
Snout pointed, definitely projecting; body elongate, slightly compressed. All spines 
and rays of marginal fins apparent but not completely developed, spines of first 
109774°— 32 6 
